﻿using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;

//页面加载显示验证码
//点击图片刷验证码

namespace WindowsFormsApplicationPlatform
{
    public partial class FrmVCode : Form
    {
        public FrmVCode()
        {
            InitializeComponent();
        }

        private void FrmVCode_Load(object sender, EventArgs e)
        {
            GetVCode();
        }
        private void picVCode_Click(object sender, EventArgs e)
        {
            GetVCode();
        }

        private void GetVCode()
        {
            string romxx = CreateNewVCode();
            this.picVCode.Image = Bitmap.FromStream(CreateNewImage(romxx));
        }

        /// <summary>
        /// 生成最新的验证码
        /// </summary>
        /// <returns></returns>
        private string CreateNewVCode()
        {
            string strOut = "";
            System.Random random = new Random();

            for (int i = 0; i < 5; i++)
            {
                string num = Convert.ToString(random.Next(10000) % 10);
                strOut += num;
            }
            return strOut.Trim();
        }
        
        private readonly Single _jianju = (float)18.0;

        private readonly Single _height = (float)24.0;

        private const double PI2 = 6.283185307179586476925286766559;

        private MemoryStream CreateNewImage(string checkCode)
        {
            MemoryStream ms = null;

            Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * _jianju)), (int)_height);

            Graphics g = Graphics.FromImage(image);

            try
            {

                Random random = new Random();

                g.Clear(Color.White);

                // 画图片的背景噪音线

                for (int i = 0; i < 18; i++)
                {

                    int x1 = random.Next(image.Width);

                    int x2 = random.Next(image.Width);

                    int y1 = random.Next(image.Height);

                    int y2 = random.Next(image.Height);

                    g.DrawLine(new Pen(Color.FromArgb(random.Next()), 1), x1, y1, x2, y2);

                }

                Font font = new System.Drawing.Font("Times New Roman", 14, System.Drawing.FontStyle.Bold);

                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

                g.DrawString(checkCode, font, brush, 2, 2);
                // 画图片的前景噪音点

                for (int i = 0; i < 150; i++)
                {

                    int x = random.Next(image.Width);

                    int y = random.Next(image.Height);

                    image.SetPixel(x, y, Color.FromArgb(random.Next()));

                }

                // 画图片的波形滤镜效果

                image = TwistImage(image, true, 3, 1);

                // 画图片的边框线

                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);

                ms = new System.IO.MemoryStream();

                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

            }

            finally
            {

                g.Dispose();

                image.Dispose();

            }

            return ms;
        }


        private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
        {

            System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);

            // 将位图背景填充为白色

            System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);

            graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);

            graph.Dispose();



            double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;



            for (int i = 0; i < destBmp.Width; i++)
            {

                for (int j = 0; j < destBmp.Height; j++)
                {

                    double dx = 0;

                    dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;

                    dx += dPhase;

                    double dy = Math.Sin(dx);



                    // 取得当前点的颜色

                    int nOldX = 0, nOldY = 0;

                    nOldX = bXDir ? i + (int)(dy * dMultValue) : i;

                    nOldY = bXDir ? j : j + (int)(dy * dMultValue);



                    System.Drawing.Color color = srcBmp.GetPixel(i, j);

                    if (nOldX >= 0 && nOldX < destBmp.Width

                     && nOldY >= 0 && nOldY < destBmp.Height)
                    {

                        destBmp.SetPixel(nOldX, nOldY, color);

                    }

                }

            }



            return destBmp;

        }



    }
}
